Yes, humans are inclined to form tribes and to fear the other, just like our primitive ancestors. It's little reason to justify such division today, and especially not to participate in mass murder to achieve it.
Not at all! To use my Bangladesh example. Bangladesh was founded in 1971 as a secular republic. Pakistan thereafter veered towards theocracy, e.g. adopting Sharia law for criminal proceedings in 1976. Subsequent events have slowly chipped away at Bangladeshi secularism over the years, but had they remained with Pakistan it would have been a lost hope. And as for tribalism being obsolete, I don't agree. There are hundreds of millions of people who think I should be executed for leaving the religion I was born into: https://www.washingtonpost.com/news/worldviews/wp/2013/05/01.... Do you want those folks voting on the laws that govern you? If not, you're not arguing against "tribalism," you're just arguing about where the tribal lines should be drawn.
But that's speculation, neither here nor there. Who knows how it would have actually played out.
I would like to agree with you but there is not evidence that humans have not changed and that
>humans are inclined to form tribes and to fear the other
remains true.
Rather we should accept we are tribal and work to ensure our collaborations, alliances and policies have that in mind. To assume that we, by virtue of just living in the present day with more technology, are more advanced and that we have progressed is a big big error.
Progress is not something that just happens. Progress is not inevitable. Societies do not naturally become more civilised. People need to work to ensure civilisation doesn't fall apart. Progress was made by people, it is the result of actions made.